Students who demonstrate understanding can: Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
Clarification statement: Examples of data include similarities of rock and fossil types on different continents, the shapes of the continents (including continental shelves), and the locations of ocean structures (such as ridges, fracture zones, and trenches).
Assessment boundary: Paleomagnetic anomalies in oceanic and continental crust are not assessed.
Official wording from the Next Generation Science Standards (NGSS Lead States, 2013). NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the NGSS were involved in the production of this page, and they do not endorse it. View on nextgenscience.org
South America and Africa look as if they could slot together like jigsaw pieces, and that observation was the starting point for one of the biggest ideas in science. Students analyze and interpret several kinds of data to argue that continents have moved: matching coastlines and continental shelves, identical rock types and mountain belts on opposite sides of oceans, fossils of land animals and plants that could not have crossed an ocean, and the pattern of ridges, fracture zones and trenches on the seafloor.
No single clue is enough on its own. Fossils of the freshwater reptile Mesosaurus in both Brazil and southern Africa are hard to explain unless the land was once joined. The fit is even better when the edges of the continental shelves, rather than the present coastlines, are matched. Mid-ocean ridges, where new seafloor forms, run down the middle of oceans, while deep trenches mark places where seafloor sinks back into the mantle.
Paleomagnetic stripes are outside the assessment boundary. Students should combine the other lines of evidence into a convincing argument.
Continents are part of rigid plates that move over the hot, slowly flowing mantle beneath them. They do not float on seawater.
Plates are still moving today, as earthquakes, volcanoes and measurements of a few centimeters per year show.
Some fossil species, like small freshwater reptiles and seed ferns, could not have crossed thousands of kilometers of ocean, which is why their distribution is strong evidence.
The jigsaw fit alone is suggestive. It is the agreement of rocks, fossils and seafloor data that makes the case strong.
Fossils of Mesosaurus, a small reptile that lived in fresh water, are found only in southern Africa and eastern South America. Use this and one other piece of evidence to argue that the continents were once joined.
Answer: The freshwater reptile's fossils and the matching rock layers both make sense only if the two continents were once joined and later drifted apart.
Give groups paper cutouts of continents, including their continental shelves, marked with fossil and rock symbols, and ask them to reconstruct the supercontinent from the evidence. A seafloor map with ridges and trenches extends the story beneath the oceans. Discuss why the idea was rejected at first and what evidence later convinced scientists.
Assessment items often provide a map or table of fossil and rock locations and ask students to interpret what it shows about past plate positions.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: C) The continents were once joined when the plant lived
The plant could not easily cross oceans, so the best explanation is that the continents were connected.
Answer: B) Shelves are the true edges of the continents, so they fit better
Sea level changes move coastlines; the shelf edge marks the real edge of continental crust and gives a closer fit.
Answer: A) New seafloor forms as plates move apart
Magma rises at ridges and forms new oceanic crust as the plates spread.
Answer: trench (also accepted: an ocean trench, ocean trench, trenches)
Deep ocean trenches mark subduction zones, where seafloor descends into the mantle.
Answer: C) They formed in one range that was later split apart
Identical rock types and ages on both sides point to one mountain range broken apart by plate motion.
Answer: Pangaea (also accepted: Pangea)
Pangaea was a supercontinent that began breaking apart about 200 million years ago.
Analyze and interpret data from maps to describe patterns of Earth’s features.
Evaluate evidence of the past and current movements of continental and oceanic crust and the theory of plate tectonics to explain the ages of crustal rocks.
Develop a model to illustrate how Earth's internal and surface processes operate at different spatial and temporal scales to form continental and ocean-floor features.
A full lesson with slides, activities and an exit ticket on evidence for past plate motions, pitched to grades 6-8 and editable in PowerPoint or Google Slides.
Make a lesson →A printable, differentiated worksheet on MS-ESS2-3 with an answer key, ready in about a minute.
Make a worksheet →Turn evidence for past plate motions into a quiz students answer online that marks itself, with a class summary for you.
Build a test →No. Paleomagnetic anomalies are not assessed; students use fossils, rocks, continental shapes and seafloor structures.
Maps of rock and fossil locations, continent outlines including shelves, and the locations of ridges, fracture zones and trenches.